Effects of Steroid Hormones and Cyclosporine A on Taurine-Transporter Activity in the RAW264.7 Cell Line

Abstract

The activity of the taurine transporter is affected by various extracellular stimuli, such as ions, hormones and stress. To assess the effects of steroid hormones and cyclosporine A (CsA) on taurine-transporter activity, the murine monocytic cell line, RAW264.7, was stimulated with dexamethasone (DM), triamcinolone (TA), cortisone (CS), hydrocortisone (HCS), prednisone (PSN), prednisolone (PSL) and methylprednisolone (MPSL) in the presence of 12-O-tetradecanoylphorbol 13-acetate (TPA). Treatment of the cell with TPA led to a significant reduction in taurine-transporter activity. However, in the case of the stimulation of the cells with steroid hormones in the presence of TPA, all of the hormones reversed the TPA-induced reduction in the taurine-transporter activity. Treatment of the cells with CsA led to a significant reduction in taurine-transporter activity, but ionomycin (IM) alone did not affect taurine-transporter activity. However, IM reversed the TPA- and CsA-induced reduction in taurine-transporter activity. These results showed that both IM and the glucocorticoid hormones reversed TPA-induced reductions in taurine-transporter activity but only IM reversed the CsA-induced reduction of transporter activity in the RAW264.7 cell line.